The present invention relates to the footwear-industry and, more specifically, the manufacturing of shoe soles provided for the use in cold countries and mountain-lands where ice and snow are steady. Under such circumstances, it is well known how hard is for everyone to keep on one""s feet. Resort to the so-called hobnailed shoes, that are technical, sturdy shoes having a right weight, may be made to avoid slipping. However, the use of such shoes is not compatible with the use of everyday shoes.
To avoid resorting to hobnailed shoes, sealskins or the like were once applied under the shoes to prevent the sole from contacting the frozen ground. Based on the same principle are rubber sheathes applied in a removable way to the shoes and carrying a number of nails or spikes on the face in contact with the ground.
Such a solution, however, has the serious drawback that the user must remove the sheathes away from the shoes whenever he goes into a residence or leaves the road to enter a building in order to avoid that the nails or spikes damage the floor. It is self-evident that the operation itself is troublesome and also implies the need for the user to carry the sheathes on him until he shall put on them again.
Russian Pat. No. 2075303 discloses an antiskid device having crankshaft, holders with spines fixed on crankshaft and pair of members for retaining spines in operating and non operating position. Both retaining members are formed as bearing for roller. Sole is provided with hole for receiving spines in non operative position. The whole device is located in a large seat wherein the device can be moved from the operating position to the non operating position.
This solution however has the drawback that parts of the device are protruding from the sole of the shoes. Furthermore, the presence of a big seat formed in the thickness of the sole reduces the mechanical strength of the sole structure.
The present invention seeks to overcome the above-mentioned problems by providing a shoe sole having a number of rigid spikes or nails on its face in contact with the ground. Such spikes or nails are not fixedly secured to the sole but can pass from an extracted position in contact with the ground to a retracted position not interfering with the trampling surface because of the combination between folding spike support means which can be overturned and grooves or recesses formed in the sole within which such spike support means can be accommodated.
In a preferred embodiment this is achieved by providing spikes or nails fixedly secured to the face of the support means directed to the ground, such support means being formed of folded small bars shaped as brackets, arches or having any other geometrical shape, all of them being received within grooves or recesses formed in the thickness of the sole, as well as by also providing support means hinged at both its ends and adapted to be overturned by 180xc2x0 into corresponding grooves which are mirror-like symmetrical to the preceding grooves.
In the first position the spikes or nails project from the sole by a length enough to grip the ground. In the second or rest position, the spikes or nails projecting from the small bars are accommodated in suitable recesses formed at the bottom of the grooves accommodating the small bars so that the lower surface of the shoe sole becomes flat without any projection.
Further features and advantages of the invention will be more readily apparent from the following detailed description with reference to the accompanying drawings which show some preferred embodiments of the invention only by way of a not limiting example.